Limbo Developer Hiring Guide

Hiring Guide for Limbo Engineers

Ask the right questions to secure the right Limbo talent among an increasingly shrinking pool of talent.

Limbo is a programming language developed in the late 1990s for the Inferno operating system by Bell Labs, the same research group responsible for creating Unix and C. It was designed to be a safer, more modern alternative to C, with features like garbage collection and strong type checking. Limbo is primarily used for distributed systems and is known for its simplicity and portability. Its syntax is similar to that of C, but it also incorporates elements from other languages such as Pascal and Alef. References for this information can be found in "The Inferno Operating System" by Dennis Ritchie and "The Limbo Programming Language" by Vita Nuova.

First 20 minutes

General Limbo knowledge and experience

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

How would you handle errors in Limbo?

In Limbo, errors are handled using exception handling constructs like 'raise', 'if' and 'rescue'.

Describe the difference between Limbo and C programming languages.

While both are used for systems programming, Limbo is more modern and includes features like garbage collection and support for distributed computing. C, on the other hand, is older and does not include these features.

What are the key features of Limbo programming language?

Key features of Limbo include strong typing, garbage collection, simple syntax, and support for distributed computing.

How would you compile a Limbo program?

To compile a Limbo program, you would use the Limbo compiler, 'limbo', followed by the name of the .b file.

What is the primary use of Limbo?

Limbo is primarily used for systems programming, as well as for applications that require distributed systems.

The hiring guide has been successfully sent to your email address.
Oops! Something went wrong while submitting the form.

What youre looking for early-on

Has the candidate demonstrated an understanding of the principles of software development?

Understanding the principles of software development, such as object-oriented programming, data structures, and algorithms, is important for a developer, regardless of the specific language they are using.

Does the candidate show a willingness to learn and adapt?

The tech industry is constantly evolving, and so the candidate's willingness to learn new skills and adapt to changes is essential for their long-term success in the role.

Can the candidate communicate effectively about their process and solutions?

Communication skills are important in any team-based work environment. The candidate's ability to explain their process and solutions can indicate their potential for collaboration and teamwork.

Is the candidate able to problem solve and debug in Limbo?

Debugging and problem-solving skills are essential for any developer. Their ability to identify and fix issues in Limbo code will be critical to their success in the role.

Has the candidate worked on projects using Limbo in the past?

Previous experience with Limbo in a practical setting can be a strong indicator of their ability to use the language in real-world applications.

Does the candidate demonstrate a strong understanding of Limbo programming language?

This is crucial as the job position requires the candidate to be proficient in Limbo. Their ability to understand and use the language effectively will determine their performance in the role.

Next 20 minutes

Specific Limbo development questions

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

Describe the difference between 'include' and 'import' in Limbo.

'Include' is used to include the contents of another file, while 'import' is used to import a module.

What are the data types available in Limbo?

Limbo supports several data types, including int, real, byte, big, string, list, array, and tuple.

How would you implement concurrency in Limbo?

Concurrency in Limbo is implemented using 'spawn' to create new threads of execution.

Describe the difference between 'ref' and 'adts' in Limbo.

'Ref' is used to create reference types, while 'adts' are abstract data types. The main difference is that 'ref' types are mutable, while 'adts' are not.

What is the purpose of the 'load' module in Limbo?

The 'load' module in Limbo is used to dynamically load modules at runtime.

The hiring guide has been successfully sent to your email address.
Oops! Something went wrong while submitting the form.

The ideal back-end app developer

What you’re looking to see on the Limbo engineer at this point.

At this point, a skilled Limbo engineer should demonstrate proficiency in software development, problem-solving skills, and a deep understanding of Limbo programming language. Red flags would include difficulty explaining complex concepts or inability to provide examples of past projects or problem-solving instances.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with Limbo.

What does this simple Limbo code do?

implement Main;
include "sys.m";
sys: Sys;

init(nil: ref Draw->Context, nil: list of string)
{
sys = load Sys Sys->PATH;
sys->print("Hello, World!\n");
}

This is a simple Limbo program that prints 'Hello, World!' to the console. It includes the 'sys.m' module, loads the Sys module, and uses the 'print' function from the Sys module to print the string.

What will be the output of this Limbo code?

implement Main;
include "sys.m";
sys: Sys;

init(nil: ref Draw->Context, nil: list of string)
{
sys = load Sys Sys->PATH;
for(i := 0; i < 5; i++)
sys->print("%d\n", i);
}

This Limbo program will print the numbers 0 through 4, each on a new line. It uses a for loop to iterate from 0 to 4 and the 'print' function from the Sys module to print each number.

What does this Limbo code do with an array?

implement Main;
include "sys.m";
sys: Sys;

init(nil: ref Draw->Context, nil: list of string)
{
sys = load Sys Sys->PATH;
arr := array of int(5);
for(i := 0; i < len arr; i++)
arr[i] = i * i;
for(i := 0; i < len arr; i++)
sys->print("%d\n", arr[i]);
}

This Limbo program creates an array of integers with 5 elements, assigns each element the square of its index, and then prints each element. It uses two for loops, one to assign the values and one to print them.

What does this Limbo code do with threads?

implement Main;
include "sys.m";
sys: Sys;

init(nil: ref Draw->Context, nil: list of string)
{
sys = load Sys Sys->PATH;
thread PrintHello()
{
sys->print("Hello from thread!\n");
}
}

This Limbo program creates a new thread that prints 'Hello from thread!' to the console. It uses the 'thread' keyword to create the new thread and the 'print' function from the Sys module to print the string.

What does this Limbo code do with a class object?

implement Main;
include "sys.m";
sys: Sys;

Rectangle: adt
{
width, height: int;
area: fn(r: self Rectangle): int;
};

area(r: self Rectangle): int
{
return r.width * r.height;
}

init(nil: ref Draw->Context, nil: list of string)
{
sys = load Sys Sys->PATH;
r := Rectangle(5, 10, area);
sys->print("Area: %d\n", r.area(r));
}

This Limbo program defines a Rectangle adt (abstract data type) with two integer fields, width and height, and a function field, area. It then creates a Rectangle object with width 5 and height 10, and prints the area of the rectangle.

What will be the output of this advanced Limbo code?

implement Main;
include "sys.m";
sys: Sys;

init(nil: ref Draw->Context, nil: list of string)
{
sys = load Sys Sys->PATH;
for(i := 0; i < 5; i++)
spawn printSquare(i);
}

printSquare(n: int)
{
sys->print("%d\n", n * n);
}

This Limbo program will print the squares of the numbers 0 through 4, each on a new line. However, because it uses the 'spawn' keyword to create a new thread for each print operation, the order in which the squares are printed is not guaranteed.

Wrap-up questions

Final candidate for Limbo role questions

The final few interview questions for a Limbo candidate should typically focus on a combination of technical skills, personal goals, growth potential, team dynamics, and company culture.

What are the limitations of Limbo?

Some limitations of Limbo include lack of support for generics, limited standard library, and lack of popularity, which means fewer resources and community support.

How would you implement object-oriented programming in Limbo?

While Limbo is not an object-oriented language, it does support some object-oriented features. For example, you can create 'adts' that act like classes, and use 'self' to refer to the current instance.

Describe the difference between 'self' and 'this' in Limbo.

'Self' refers to the current instance of a module, while 'this' refers to the current instance of an object.

What is the purpose of the 'sys' module in Limbo?

The 'sys' module in Limbo provides functions for system-level operations, such as file I/O and process management.

How would you implement a distributed system in Limbo?

A distributed system in Limbo can be implemented using the 'Net' module, which provides functions for network communication.

The hiring guide has been successfully sent to your email address.
Oops! Something went wrong while submitting the form.

Limbo application related

Product Perfect's Limbo development capabilities

Beyond hiring for your Limbo engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in Limbo projects, and can engage in multiple capacities.